tests/test-revert

Fix hg push and hg push -r sometimes creating new heads without --force.
Fixing issue179.

The algorithm checks if there not more new heads on the remote side than heads
which become non-heads due to getting children.

Pushing this repo:
    m
   /\
3 3a|
|/  /
2 2a
|/
1

to a repo only having 1, 2 and 3 didn't abort requiring --force before.

Added test cases for this and some doc strings for used methods.

#!/bin/sh

hg init
echo 123 > a
echo 123 > c
hg add a c
hg commit -m "first" -d "1000000 0" a c
echo 123 > b
echo %% should show b unknown
hg status
echo 12 > c
echo %% should show b unknown and c modified
hg status
hg add b
echo %% should show b added and c modified
hg status
hg rm a
echo %% should show a removed, b added and c modified
hg status
hg revert a
echo %% should show b added and c modified
hg status
hg revert b
echo %% should show b unknown and c modified
hg status
hg revert c
echo %% should show b unknown
hg status
echo %% should show a b and c
ls

true